Referring to FIG. 7, a prior art caster is illustrated. The caster includes a wheel 10 one side of which is pivotally connected to a bearing seat 2o. A center of the leg wheel has an axial hole 11 for being engaged with an axial tube 23 of the supporting seat 20. The supporting seat 20 is formed by a round mask 21 and a vertical tube 22 at one lateral side of the mask 21. The mask 21 has an opening. The axial tube 23 protrudes axially from the opening. An axial rod 30 is tightly coupled to a hole of the axial tube 23. One end thereof is formed with stop 31. Thereby, by above components, when the axial tube 23 of the supporting seat 20 is coupled to the axial hole 11 of the wheel 10. The axial rod 30 is pivotally installed to the axial tube 23 for assembling the wheel 10 and the supporting seat 20 so that the wheel 10 can rotate freely. The defect of above structure is that no braking device is installed therein.